In the following you will be guided through an analysis of
length-frequency data, resulting in an estimation of the degree of
exploitation, and an indication of how much more could be caught with a
different fishing strategy.
For advanced users we also provide an approach to estimate Linf, Z/K, Z,
annual reproductive rate (alpha), intrinsic rate of population increase
(rmax), population doubling time (td), and fishing mortality associated with maximum
sustainable yield (Fmsy).
We assume that you have a set of length
frequency data for this species and that you have a good idea about the
maximum length (largest fish caught during the last 5 - 10 years) of
your population. Note that this analysis is based on the assumption that
the size distribution in your sample is similar to that of the
population as a whole (see Note). In every step you can click on the 'Background'
button for definitions of parameters and equations.
In the next step you will be asked to enter your Length Frequency data (go to 'Length frequencies',
'L-F Data'
if you want to use data from FishBase).

Note: It is assumed here (1) that the L-F sample covers a wide range of
lengths, (2) that gear selection is accounted for and (3) that the sizes
of monthly samples are more or less equal if the total sample is
accumulated over more than one month. Accumulated samples should include
altogether at least 500 specimens. If L-F data stem from a single sample
it should include at least 1000 specimens. A good sample would be
accumulated over 6 or more months and include over 1500 specimens.